This invention relates to programmable thermostats and in particular to the display capabilities of such thermostats.
Programmable thermostats have heretofore included alphanumeric displays located within the thermostat. These displays are typically located on the front of the thermostat so as to be viewable by a person making selections as to set point temperatures that are to occur at various times of the day or night. The size of these displays is constrained by virtue of the limited space available for such displays on the front panel of the thermostat. As a result, the displays are relatively small resulting in only limited information being displayed. There is no room for on-screen instructions as to how to program the thermostat.
What is needed is a thermostat with a capability to legibly display more information than is permitted on the front face of the thermostat.
A thermostat is provided with an image projection capability that allows images concerning the operation of the thermostat to be projected onto a surface in the vicinity of the thermostat. The image projection is preferably accomplished by directing an internally generated image to an image enlargement device which thereafter projects an enlarged image onto the surface in the vicinity of the thermostat. The image is preferably generated by a microprocessor and displayed on an internal image forming device located within the body of the thermostat. One or more mirrors or prisms located within the body of the thermostat transfer the image to the image enlargement device which is preferably a convex mirror. The enlargement device is preferably mounted within a housing located on a top front portion of the thermostat so as to maximize the projection length onto the surface in the vicinity of the thermostat. The surface that receives the projected image is preferably defined by a screen affixed to the wall that the thermostat is mounted to.